Regarding my previous post, the Nature Made fish oil I use does have the USP verified seal on the bottle, for what that is worth. The bottle says the fish comes from deep ocean waters and not farm raised. The bottle lists PCBs as less than 0.09 parts per million (based on 7 indicator PCBs, but I hear there are so many indicators you cannot test for all of them from a practical standpoint) dioxins and furans as less than 2 parts per trillion WHO TEQs, and Mercury at below a limit of 0.1 parts per million.

The only fish sources listed on the bottle are anchovy and sardine. Tocopherol is also listed in the ingredients.

The bottle says that the USP has tested and verified ingredients, potency, and manufacturing processes, but it does not state that the USP has verified purity.

It looks to me like the IFOS http://www.nutrasource.ca/ifos/Default.aspx  might be the best verification system for fish oil, but do any of these organizations address oxidation and rancidity?

John,

It's not easy to tell if processed oils are oxidized or on the beginning stages of rancidity. By reading some of my researched articles, you've probably by now figured out that I don't support the consumption of processed oils, especially fish oils. Unless, fish oil is used to replace a more questionable prescription drug. However if you feel that you need to take processed oils like fish oil, here are some precautions;

Bite into the gel cap and taste the oil. If it tastes rancid through the whole bottle away. Oil in the late stages of oxidation with taste and smell rancid. Unfortunately, many manufactures are putting lemon oil and other flavorings in the fish oil to mask the "fishy" taste which also masks the rancidity. Good for sales, bad for the informed consumer. In the early stages of lipid peroxidation it is nearly impossible to detect by taste or smell.

Think of it this way. It's like habitually hitting your finger with a hammer and then taking Celebrex. Many people gulp down oxidized oils in many forms and then take antioxidants in the hope that it will counter the free radical damage. You want to minimize your exposure and risk as much as possible in the first place. Get your essential fatty acids from the freshest source possible; consumed as close and quickly to the way it came from nature.

As a side note, I think one reason why some EPA and DHA studies show ineffective results using commercial fish oil supplements is because the researchers unknowingly use oxidized or even rancid oils that throw the whole experiment off.

Okay, back to the precautions.

Buy fish oils in dark glass bottles. Oxygen can get through plastic but can't get through glass. light can get through clear bottles, but harder with blue or dark amber. It's better if you can find a manufacture that packages the individual gel caps in opaque, nitrogen filled blister packs. That's not going to guarantee complete freedom from oxidation since the gel caps are not impervious to air either, but it's a better choice.

As far as the PCBs, dioxins, and mercury is concerned, that was a major concern with fish oils and the main areas that manufactures were focused on. They did a good job cleaning that up but many never addressed the lipid peroxidation concern. They relied on previous, outdated studies on vitamin E, and as long as it contained vitamin E they assumed it was safe.

Many of the nutritional oils sold are by-products of the fishing industry and filleting process. Fish come into port. In some cases they're flash frozen and in other cases they are shipped cold to a processing plant. The fish is thawed, processed and the scraps are pressed for their oils. Imagine all of the time in transit and processing and exposure to oxygen that occurs before any antioxidants are mixed with the oils.

Here is a short, interesting article to read LINK

Hi Tom,

Thanks for the additional info.

I think it makes sense to keep all food products, especially fish oil, as fresh as possible, both in processing and storage. It seems reasonable to conclude that other food products, fruits, vegetables, and meats that are starting to oxidize may also not be ideal as opposed to super fresh produce. I think the problem is that we don't really know to what extent this may be a problem. Problems from oxidized food are not going to readily present themselves, you would have to really study the issue with trials to get any real answers. Obviously, the fresher the better.

I think that all fish oil manufacturers should try to fully address the issues of oxidation and rancidity, better safe than sorry. They also need to do some studies with many people, different dosages, and with several brands of fish oil, then compare this with people eating fish without supplements.

If the fish oils supplements are oxidizing, I would suspect that the oil in the fish is also oxidizing during processing and storage, so eating fish may not be that much better. Plus, the fish is going through the cooking process and I suspect that might make matters worse as far as oxidizing the oils in the fish, especially if it were overcooked or charred.

Here is an article I found that says fish oil oxidation is not real a problem; do you think any of their points are valid? Their references are at the bottom of the page.

http://newsletter.vitalchoice.com/e_article001852076.cfm

Since upping my fish oil intake to 1,440 mg of omega-3 per day and upping my vitamin D to 2,000 IU per day, I have noticed less anxiety, and my blood pressure is good. I'm not a big fish eater and usually when I eat it, it's Cod, which is not as high in omega-3 as salmon. I used to eat the canned salmon but I'm not crazy about it, fillet salmon is good but kind of pricey. Sardines have a great nutritional profile, are high in omega-3, and cost effective, but they say they have pcb's in them so I stopped eating them.

I am going to keep taking fish oil supplements, but I am also going to keep researching this issue and look for the best brands and companies who utilize practices that are likely to provide the lowest levels of oxidation. It's probably also especially important with fish oil to remember to check the expiration dates on the bottles and buy as fresh as possible. Something in a dark glass bottle filled with unflavored fish oil you can put on a spoon may be ideal so you can keep an eye on how it looks, smells, and tastes. I like glass for storing anything we drink, I have always been suspect of problems with plastic containers chemically interacting with things we drink, but that's another topic.

In this link http://www.youtube.com/watch?v=JKU0MkqNAN0  Dr. Oz talks about what supplements he takes everyday.

Dr. Oz says he uses a plankton based supplement for omega-3, since this is where the fish get the omega-3 in the first place. What do you think of plankton as a source of omega-3 ? I'm not sure how it would compare to fish oil as far as rancidity, oxidation, purity, and consistency.

Also, just because a person and/or organization has a business interest in a subject doesn't automatically make their data/info biased or incorrect.

I make one post and you go off and say I got my "feathers ruffled" when you are the one putting out post after post against fish oil, etc. You automatically dismiss any who disagree with you and adopt a superior attitude. In internet circles this is usually evidence of a troll.

By the way here are some references that do NOT support your viewpoint.

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Erdogan H, Fadillioglu E, Ozgocmen S, Sogut S, Ozyurt B, Akyol O, Ardicoglu O. Effect of fish oil supplementation on plasma oxidant/antioxidant status in rats. Prostaglandins Leukot Essent Fatty Acids. 2004 Sep;71(3):149-52.
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Higdon JV, Liu J, Du SH, Morrow JD, Ames BN, Wander RC. Supplementation of postmenopausal women with fish oil rich in eicosapentaenoic acid and docosahexaenoic acid is not associated with greater in vivo lipid peroxidation compared with oils rich in oleate and linoleate as assessed by plasma malondialdehyde and F(2)-isoprostanes. Am J Clin Nutr. 2000 Sep;72(3):714-22.
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Iraz M, Erdogan H, Ozyurt B, Ozugurlu F, Ozgocmen S, Fadillioglu E. Brief communication: omega-3 essential fatty acid supplementation and erythrocyte oxidant/antioxidant status in rats. Ann Clin Lab Sci. 2005 Spring;35(2):169-73.
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Mas E, Woodman RJ, Burke V, Puddey IB, Beilin LJ, Durand T, Mori TA. The omega-3 fatty acids EPA and DHA decrease plasma F(2)-isoprostanes: Results from two placebo-controlled interventions. Free Radic Res. 2010 Jun 14.
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Mori TA, Woodman RJ, Burke V, Puddey IB, Croft KD, Beilin LJ. Effect of eicosapentaenoic acid and docosahexaenoic acid on oxidative stress and inflammatory markers in treated-hypertensive type 2 diabetic subjects. Free Radic Biol Med. 2003 Oct 1;35(7):772-81.
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Nalsen C, Vessby B, Berglund L, Uusitupa M, Hermansen K, Riccardi G, Rivellese A, Storlien L, Erkkila A, Yla-Herttuala S, Tapsell L, Basu S. Dietary (n-3) fatty acids reduce plasma F2-isoprostanes but not prostaglandin F2alpha in healthy humans. J Nutr 2006;136:1222 – 1228.
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Palozza P, Sgarlata E, Luberto C, Piccioni E, Anti M, Marra G, Armelao F, Franceschelli P, Bartoli GM. n-3 fatty acids induce oxidative modifications in human erythrocytes depending on dose and duration of dietary supplementation. Am J Clin Nutr. 1996 Sep;64(3):297-304. Accessed at http://www.ajcn.org/cgi/reprint/64/3/297
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Quaggiotto P, Leitch JW, Falconer J, Murdoch RN, Garg ML. Plasma F2[alpha]-isoprostane levels are lowered in pigs fed an (n-3) polyunsaturated fatty acid supplemented diet following occlusion of the left anterior descending coronary artery. Nutr Res 2000;20:675 – 684.
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Richard D, Kefi K, Barbe U, Bausero P, Visioli F. Polyunsaturated fatty acids as antioxidants. Pharmacol Res. 2008 May 18. [Epub ahead of print]
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Thies F, Garry JM, Yaqoob P, Rerkasem K, Williams J, Shearman CP, Gallagher PJ, Calder PC, Grimble RF. Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial. Lancet. 2003 Feb 8;361(9356):477-85.
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Wander RC, Du SH. Oxidation of plasma proteins is not increased after supplementation with eicosapentaenoic and docosahexaenoic acids. Am J Clin Nutr. 2000 Sep;72(3):731-7.

Daily Exposure to PCBs, total (ng/day)
12.184 Solgar Norwegian Cod Liver Oil
27.272 TwinLab Norwegian Cod Liver Oil
29.816 GNC Liquid Norwegian Cod Liver Oil
39.121 TwinLab Emulsified Norwegian Cod Liver Oil
44.2 Solgar 100% Pure Norwegian Shark Liver Oil Complex
59.256 Nature Made Odorless Fish Oil
85.871 Now Foods Shark Liver Oil
240.65 Nature Made Cod Liver Oil
643.35 Now Foods Double Strength Cod Liver Oil
852.18 Now Foods Salmon Oil

Daily Exposure to PCBs, toxicity-weighted (pg/day)
0.05561 TwinLab Norwegian Cod Liver Oil
0.0933 Solgar 100% Pure Norwegian Shark Liver Oil Complex
0.096724 TwinLab Emulsified Norwegian Cod Liver Oil
0.1368 Nature Made Odorless Fish Oil
0.741182 Solgar Norwegian Cod Liver Oil
1.12256 Now Foods Double Strength Cod Liver Oil
1.2096 Now Foods Salmon Oil
2.14114 GNC Liquid Norwegian Cod Liver Oil
4.11141 Now Foods Shark Liver Oil
12.0691 Nature Made Cod Liver Oil

pg/day = picogram per day = trillionths of gram per day (the usual measurement unit for dioxin-equivalent toxicity).

https://org2.democracyinaction.org/o/6491/images/Prop%2065%20fish%20oil%20press%20release.pdf